This invention relates to photography and more particularly, to novel photosensitive photographic elements, particularly novel photosensitive emulsions.
As a result of the known disadvantages of gelatin, in particular, its variable photographic properties and its fixed physical properties, for example, its diffusion characteristics; much effort has been expended in the past in order to replace gelatin with a suitable synthetic grain-growing protective colloid for photographic silver halide emulsions. Many synthetic polymeric materials have heretofore been suggested as peptizers for silver halide emulsions, however, these have generally not functioned satisfactory and frequently have not fulfilled all of the basic requirements for a photosensitive silver halide emulsion grain-growing protective colloid listed following:
(1) ABSENT (OR CONSTANT) PHOTOGRAPHIC ACTIVITY;
(2) ABILITY TO FORM AN ADSORPTION LAYER ON MICROCRYSTALS OF SILVER HALIDE PERMITTING STABLE SUSPENSIONS TO BE OBTAINED;
(3) ABILITY TO FORM ADSORPTION LAYERS AS DESCRIBED IN (2) ABOVE WHICH DO NOT PREVENT GROWTH OF SILVER HALIDE MICROCRYSTALS DURING PHYSICAL RIPENING; AND
(4) SOLUBILITY IN WATER SOLUTION.
In addition, hithertofore, much emphasis has been placed on the ability of the snythetic polymeric material to mix with gelatin, as this property has been critical for employment in partial substitution reactions with gelatin. Consequently, many synthetic polymers of the prior art have been water-insoluble lattices which allow for the growth of silver halide crystals only in the presence of gelatin.
It is known from McDowell, U.S. Pat. No. 3,589,906 that certain perfluoro compounds, particularly those derived from saturated perfluoro carboxylic acids, perfluorosulfonic acids or perfluorosulfuric acids, are useful in photographic emulsions to eliminate repellency spots in coatings but not as emulsions peptizers. Certain halogenated vinyl compounds such as vinylchloride, have been employed as monomers in the preparation of synthetic silver halide emulsion binders, for example as described in Caldwell, U.S. Pat. No. 2,843,562; however, it has been heretofore unknown to employ polymers or copolymers having repeating halogenated acrylate units as peptizers.